Two-filament street-series lamp



April 20 1926! r 1,581,690

A. L. POWELL TWO-EILAMENT STREET SERIES LAMP Filed Dec. 19 1 1 INVENTORARTHUR L- powzu.

ATTOYRNEY the leading-in wire 4,- filament 9 and the leading-in wirethus, the filament 9 is normally maintained in circuit. The filament 9may, however, burn out or be ruptured in some manner, thereby preventingthe passage of current. It is then desirable to engage another filamentin order to'maintain the continuous luminosity of the lamp as well as toprevent the series; circuit'from becoming disrupted. a

The present embodiment of the invention provides a secondary filamentl0, preferably of the same current rating as the primary filament andhaving its ends connected to the leading-in wire 5 and to an auxiliaryor supplemental conductor 11. This conductor is provided with aprojection 12 and is adapted to be positioned with the said projectionadjacent, and preferably parallel, to the end 8 of the leading-in wire4. It has been found desirable to-support the supplemental conductor 11by a glass head 13 with sufficient material intermediate the leadinginwire and the conductor to afford adequate insulation. The supplementalconductor 1]. is juxtaposed with respect to the leading-in wire 4 so asto provide a relatively small gap 14-between the projection 12 and theend 8' of the leading-in wire.

The leading-in wires are usually made of nickel and are consequently,readily fusible. Thus, if the primary filament breaks and the circuit isthus disrupted, an arc will be first produced between the broken ends ofthe filament and, as the filament wire melts, the are will continuebetween the leading-in wire 5 and the end 8 of the leading-in wire 4,whereupon the ends of the. leading-in wires will become molten and-theend 8 of the leading-in wire 4 will quickly drop and make contact withthe end 12 of the sup-.

plemental conductor 11, or. an enlargement or bead will form on theleading-in wire and span the gap 14, thereby joining the.

leading-in wire 4 to the conductor. The resistance being less in the,circuit formed throughthe connection between the leadingin wire 4 andthe supplemental conductor 11 than in the arc gap, the current will thenpass through the leading-in wire 4, the conductor 11, the filament 10and thence through the leading-inwire 5, and cause the filament 10 tobecome incandescent.

It is obvious that, if desirable, the filament 10 might be. dispensedwith, in which case, the conductor 11 would be connected to theleading-in wire 5. lVith this construction, substantially the sameadvantage would be obtained as abowe described, inasmuch as provision ismade for a continuation of the passage of current upon the failure ofthe filament 9; the are being again employed to perform the function ofclosing the circuit as is the case in the employment of the twofilaments.

The end 8' of the leading-in wire 4 and the end 12 of the conductor 11are so posi tioned with respect to each other as to provide a gap-14 ofsuch dimension that, if the filament breaks when cold, the line voltage"0 will jump the gap and cause a fusing of the end 8 to the supplementalconductor 11, thus putting in circuit the secondary filament or in theevent that the secondary filament is omitted, a connection will be madeand the continuity of the circuit will be maintained.

A lamp provided with the present invention may be burned in practicallyany position. For instance, if the lamp is placed in service with thetip down,;a break in the filament will first cause an arc tobe producedbetween the ends thereof and then between .the leading-in wire wire 5and the end '8 of the leading-in wire 4. This are will cause the end ofthe leading-in wires to fuse and pro: (luc an accumulation of metal, inother words, form a bead or ball at the ends of the leading-in wires.The accumulation of metal thus formed at the end 8 will efiec't abridging of the gap 14 to out in the filament 10 or close the circuit,in the event that the filament 10 is omitted.

It is evident that the present invention may be applied in anexpeditious and economic manner to the type of lamp illustratedwithoutany alteration in the standard 0011- e struction. Any commerciallamp of this type may be equipped with the present invention duringmanufacture, at which time the supplemental conductor may besecured tothe leading-in wire or to any other suitable portion of the structure,and the filament may be connected between the said conductor and theopposite leading-in.wire.

I have shown and described one form of a device which has been found adesirable. embodiment of the invention, it is, however, to be understoodthat the invention is not restricted to the structural. details shownand that many modifications may be made therein without departing fromthe spirit and scope of the invention as set forth in the appendedclaims.

What is claimed is:

1. An electric lamp comprising a filament, leading-in wires connected toopposite ends of said filament, a supplemental'conductor supported byand insulated from one of said leading-in wires, conducting meansbetween said'supplemental conductor and the other one of said lgding-in'wires, one end of said conductor be: g positioned in nearrelation to an end of the supporting leading-in wire, whereby an areproduced by a break in said filament fuses said leading-in wire and saidconductor to provide a closed circuit.

2. An electric lamp comprising leading-in wires of relatively largediameter and low fusing point, a primary filament having its endsconnected tothe exposed ends of saidported upon and insulated from oneof said leading-in wires, one'end of said conductor being spaced fromthe end of the leading-in wire upon which it is supported, theoppositeend of said supplemental conductor being connected to the otherleading-in wire by an auxiliaryfila1nent, whereby an are created bfailure of the primary filament effects a fusion of the adjacent ends ofthe leading-in wire and the auxiliary conductor supported thereon,causing said auxiliary filament to be put in circuit.

An electric lamp comprising a primary and a secondary filament,conductors of relatively low fusing point being connected to saidfilaments, said secondary filament being normally maintained out ofcircuit by a gap between the conductor connected thereto and theconductor connected to the primary filament, whereby the are createdwhen said primary filament fails, operates to fuse said material andclose said gap to connect said secondary filament in circuit,

4. An electric lamp comprising a stem having a. press, leading-in wiressecured in said press, a filament connecting the ends of said leading-inwires, a supplemental con ductor supported by and insulated from one ofsaid leading-in wires, one end of said conductor-being positioned,adjacent to one of said leading-in wires to provide a gap therebetween,and a filament connecting said conductor and the other leading-in wire,said gap being of such width that an arc will pass thereover upon thefailure of said 1nemtioned filament and cause said supplementalconductor and adjacent leading-in wire to be welded together.

5. An electric lamp comprising leading-in wires, a primary-filamentconnected to the ends of said leading-in wires and normally in circuit,at least one of said wires being of a metal of relatively low fusingpoint, a supplemental conductor supported by and insulated from said lowfusing point leading-in wire, a secondary filament connected to theother leading-in wire and to said supplemental conductor, the relativepositions of a portion of the leading-in wire supporting thesupplemental conductor and a portion of said conductor being such, thatupon a failure of the primary filament, said conductor and leading-inwire will become

